Although landfills have evolved into highly engineered and regulated structures, selecting appropriate locations remains controversial. It is imperative that proper objectives and site selection criteria be established for siting new landfills. An expert system for siting landfills was designed and implemented. The following data was incorporated into the GIS system: topography, soil, geology, hydrology, precipitation, roads, land use, and population. Thus the task of screening potential sites was performed quickly and reliably. The significance of the project was in developing a coherent set of siting criteria and establishing a robust methodology for analyzing the necessary data for Lebanon.